16 files changed, 185 insertions, 65 deletions

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 37755d621924..a6e729766821 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -82,7 +82,7 @@ static kdbtab_t kdb_base_commands[50];
 #define for_each_kdbcmd(cmd, num)                                       \
         for ((cmd) = kdb_base_commands, (num) = 0;                      \
              num < kdb_max_commands;                                    \
-             num == KDB_BASE_CMD_MAX ? cmd = kdb_commands : cmd++, num++)
+             num++, num == KDB_BASE_CMD_MAX ? cmd = kdb_commands : cmd++)
 
 typedef struct _kdbmsg {
         int     km_diag;        /* kdb diagnostic */
@@ -646,7 +646,7 @@ static int kdb_defcmd2(const char *cmdstr, const char *argv0)
         }
         if (!s->usable)
                 return KDB_NOTIMP;
-        s->command = kmalloc((s->count + 1) * sizeof(*(s->command)), GFP_KDB);
+        s->command = kzalloc((s->count + 1) * sizeof(*(s->command)), GFP_KDB);
         if (!s->command) {
                 kdb_printf("Could not allocate new kdb_defcmd table for %s\n",
                            cmdstr);
@@ -2361,7 +2361,7 @@ static int kdb_pid(int argc, const char **argv)
  */
 static int kdb_ll(int argc, const char **argv)
 {
-        int diag;
+        int diag = 0;
         unsigned long addr;
         long offset = 0;
         unsigned long va;
@@ -2400,20 +2400,21 @@ static int kdb_ll(int argc, const char **argv)
                 char buf[80];
 
                 if (KDB_FLAG(CMD_INTERRUPT))
-                        return 0;
+                        goto out;
 
                 sprintf(buf, "%s " kdb_machreg_fmt "\n", command, va);
                 diag = kdb_parse(buf);
                 if (diag)
-                        return diag;
+                        goto out;
 
                 addr = va + linkoffset;
                 if (kdb_getword(&va, addr, sizeof(va)))
-                        return 0;
+                        goto out;
         }
-        kfree(command);
 
-        return 0;
+out:
+        kfree(command);
+        return diag;
 }
 
 static int kdb_kgdb(int argc, const char **argv)
@@ -2739,13 +2740,13 @@ int kdb_register_repeat(char *cmd,
                 }
                 if (kdb_commands) {
                         memcpy(new, kdb_commands,
-                               kdb_max_commands * sizeof(*new));
+                          (kdb_max_commands - KDB_BASE_CMD_MAX) * sizeof(*new));
                         kfree(kdb_commands);
                 }
                 memset(new + kdb_max_commands, 0,
                        kdb_command_extend * sizeof(*new));
                 kdb_commands = new;
-                kp = kdb_commands + kdb_max_commands;
+                kp = kdb_commands + kdb_max_commands - KDB_BASE_CMD_MAX;
                 kdb_max_commands += kdb_command_extend;
         }
 
diff --git a/kernel/futex.c b/kernel/futex.c
index 6c683b37f2ce..40a8777a27d0 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2489,7 +2489,8 @@ void exit_robust_list(struct task_struct *curr)
 {
         struct robust_list_head __user *head = curr->robust_list;
         struct robust_list __user *entry, *next_entry, *pending;
-        unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip;
+        unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
+        unsigned int uninitialized_var(next_pi);
         unsigned long futex_offset;
         int rc;
 
diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
index 06da4dfc339b..a7934ac75e5b 100644
--- a/kernel/futex_compat.c
+++ b/kernel/futex_compat.c
@@ -49,7 +49,8 @@ void compat_exit_robust_list(struct task_struct *curr)
 {
         struct compat_robust_list_head __user *head = curr->compat_robust_list;
         struct robust_list __user *entry, *next_entry, *pending;
-        unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip;
+        unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
+        unsigned int uninitialized_var(next_pi);
         compat_uptr_t uentry, next_uentry, upending;
         compat_long_t futex_offset;
         int rc;
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 2c9120f0afca..e5325825aeb6 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -620,7 +620,7 @@ static struct pmu perf_breakpoint = {
         .read           = hw_breakpoint_pmu_read,
 };
 
-static int __init init_hw_breakpoint(void)
+int __init init_hw_breakpoint(void)
 {
         unsigned int **task_bp_pinned;
         int cpu, err_cpu;
@@ -655,6 +655,5 @@ static int __init init_hw_breakpoint(void)
 
         return -ENOMEM;
 }
-core_initcall(init_hw_breakpoint);
 
 
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index f16763ff8481..90f881904bb1 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -145,7 +145,9 @@ void irq_work_run(void)
                  * Clear the BUSY bit and return to the free state if
                  * no-one else claimed it meanwhile.
                  */
-                cmpxchg(&entry->next, next_flags(NULL, IRQ_WORK_BUSY), NULL);
+                (void)cmpxchg(&entry->next,
+                              next_flags(NULL, IRQ_WORK_BUSY),
+                              NULL);
         }
 }
 EXPORT_SYMBOL_GPL(irq_work_run);
diff --git a/kernel/module.c b/kernel/module.c
index 437a74a7524a..d190664f25ff 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2326,6 +2326,18 @@ static void find_module_sections(struct module *mod, struct load_info *info)
         kmemleak_scan_area(mod->trace_events, sizeof(*mod->trace_events) *
                            mod->num_trace_events, GFP_KERNEL);
 #endif
+#ifdef CONFIG_TRACING
+        mod->trace_bprintk_fmt_start = section_objs(info, "__trace_printk_fmt",
+                                         sizeof(*mod->trace_bprintk_fmt_start),
+                                         &mod->num_trace_bprintk_fmt);
+        /*
+         * This section contains pointers to allocated objects in the trace
+         * code and not scanning it leads to false positives.
+         */
+        kmemleak_scan_area(mod->trace_bprintk_fmt_start,
+                           sizeof(*mod->trace_bprintk_fmt_start) *
+                           mod->num_trace_bprintk_fmt, GFP_KERNEL);
+#endif
 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
         /* sechdrs[0].sh_size is always zero */
         mod->ftrace_callsites = section_objs(info, "__mcount_loc",
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index cb6c0d2af68f..671f6c8c8a32 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -31,6 +31,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/perf_event.h>
 #include <linux/ftrace_event.h>
+#include <linux/hw_breakpoint.h>
 
 #include <asm/irq_regs.h>
 
@@ -2234,11 +2235,6 @@ int perf_event_release_kernel(struct perf_event *event)
         raw_spin_unlock_irq(&ctx->lock);
         mutex_unlock(&ctx->mutex);
 
-        mutex_lock(&event->owner->perf_event_mutex);
-        list_del_init(&event->owner_entry);
-        mutex_unlock(&event->owner->perf_event_mutex);
-        put_task_struct(event->owner);
-
         free_event(event);
 
         return 0;
@@ -2251,9 +2247,43 @@ EXPORT_SYMBOL_GPL(perf_event_release_kernel);
 static int perf_release(struct inode *inode, struct file *file)
 {
         struct perf_event *event = file->private_data;
+        struct task_struct *owner;
 
         file->private_data = NULL;
 
+        rcu_read_lock();
+        owner = ACCESS_ONCE(event->owner);
+        /*
+         * Matches the smp_wmb() in perf_event_exit_task(). If we observe
+         * !owner it means the list deletion is complete and we can indeed
+         * free this event, otherwise we need to serialize on
+         * owner->perf_event_mutex.
+         */
+        smp_read_barrier_depends();
+        if (owner) {
+                /*
+                 * Since delayed_put_task_struct() also drops the last
+                 * task reference we can safely take a new reference
+                 * while holding the rcu_read_lock().
+                 */
+                get_task_struct(owner);
+        }
+        rcu_read_unlock();
+
+        if (owner) {
+                mutex_lock(&owner->perf_event_mutex);
+                /*
+                 * We have to re-check the event->owner field, if it is cleared
+                 * we raced with perf_event_exit_task(), acquiring the mutex
+                 * ensured they're done, and we can proceed with freeing the
+                 * event.
+                 */
+                if (event->owner)
+                        list_del_init(&event->owner_entry);
+                mutex_unlock(&owner->perf_event_mutex);
+                put_task_struct(owner);
+        }
+
         return perf_event_release_kernel(event);
 }
 
@@ -5677,7 +5707,7 @@ SYSCALL_DEFINE5(perf_event_open,
         mutex_unlock(&ctx->mutex);
 
         event->owner = current;
-        get_task_struct(current);
+
         mutex_lock(&current->perf_event_mutex);
         list_add_tail(&event->owner_entry, &current->perf_event_list);
         mutex_unlock(&current->perf_event_mutex);
@@ -5745,12 +5775,6 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
         ++ctx->generation;
         mutex_unlock(&ctx->mutex);
 
-        event->owner = current;
-        get_task_struct(current);
-        mutex_lock(&current->perf_event_mutex);
-        list_add_tail(&event->owner_entry, &current->perf_event_list);
-        mutex_unlock(&current->perf_event_mutex);
-
         return event;
 
 err_free:
@@ -5901,8 +5925,24 @@ again:
  */
 void perf_event_exit_task(struct task_struct *child)
 {
+        struct perf_event *event, *tmp;
         int ctxn;
 
+        mutex_lock(&child->perf_event_mutex);
+        list_for_each_entry_safe(event, tmp, &child->perf_event_list,
+                                 owner_entry) {
+                list_del_init(&event->owner_entry);
+
+                /*
+                 * Ensure the list deletion is visible before we clear
+                 * the owner, closes a race against perf_release() where
+                 * we need to serialize on the owner->perf_event_mutex.
+                 */
+                smp_wmb();
+                event->owner = NULL;
+        }
+        mutex_unlock(&child->perf_event_mutex);
+
         for_each_task_context_nr(ctxn)
                 perf_event_exit_task_context(child, ctxn);
 }
@@ -6321,6 +6361,8 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
 
 void __init perf_event_init(void)
 {
+        int ret;
+
         perf_event_init_all_cpus();
         init_srcu_struct(&pmus_srcu);
         perf_pmu_register(&perf_swevent);
@@ -6328,4 +6370,7 @@ void __init perf_event_init(void)
         perf_pmu_register(&perf_task_clock);
         perf_tp_register();
         perf_cpu_notifier(perf_cpu_notify);
+
+        ret = init_hw_breakpoint();
+        WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
 }
diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
index c7a8f453919e..aeaa7f846821 100644
--- a/kernel/pm_qos_params.c
+++ b/kernel/pm_qos_params.c
@@ -121,10 +121,10 @@ static inline int pm_qos_get_value(struct pm_qos_object *o)
 
         switch (o->type) {
         case PM_QOS_MIN:
-                return plist_last(&o->requests)->prio;
+                return plist_first(&o->requests)->prio;
 
         case PM_QOS_MAX:
-                return plist_first(&o->requests)->prio;
+                return plist_last(&o->requests)->prio;
 
         default:
                 /* runtime check for not using enum */
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 6842eeba5879..05bb7173850e 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -37,13 +37,13 @@ static int check_clock(const clockid_t which_clock)
         if (pid == 0)
                 return 0;
 
-        read_lock(&tasklist_lock);
+        rcu_read_lock();
         p = find_task_by_vpid(pid);
         if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
-                   same_thread_group(p, current) : thread_group_leader(p))) {
+                   same_thread_group(p, current) : has_group_leader_pid(p))) {
                 error = -EINVAL;
         }
-        read_unlock(&tasklist_lock);
+        rcu_read_unlock();
 
         return error;
 }
@@ -390,7 +390,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
 
         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
 
-        read_lock(&tasklist_lock);
+        rcu_read_lock();
         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
                 if (pid == 0) {
                         p = current;
@@ -404,7 +404,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
                         p = current->group_leader;
                 } else {
                         p = find_task_by_vpid(pid);
-                        if (p && !thread_group_leader(p))
+                        if (p && !has_group_leader_pid(p))
                                 p = NULL;
                 }
         }
@@ -414,7 +414,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
         } else {
                 ret = -EINVAL;
         }
-        read_unlock(&tasklist_lock);
+        rcu_read_unlock();
 
         return ret;
 }
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 29bff6117abc..a5aff3ebad38 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -246,9 +246,13 @@ config PM_OPS
         depends on PM_SLEEP || PM_RUNTIME
         default y
 
+config ARCH_HAS_OPP
+        bool
+
 config PM_OPP
         bool "Operating Performance Point (OPP) Layer library"
         depends on PM
+        depends on ARCH_HAS_OPP
         ---help---
           SOCs have a standard set of tuples consisting of frequency and
           voltage pairs that the device will support per voltage domain. This
diff --git a/kernel/sched.c b/kernel/sched.c
index aa14a56f9d03..dc91a4d09ac3 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -560,18 +560,8 @@ struct rq {
 
 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
 
-static inline
-void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
-{
-        rq->curr->sched_class->check_preempt_curr(rq, p, flags);
 
-        /*
-         * A queue event has occurred, and we're going to schedule.  In
-         * this case, we can save a useless back to back clock update.
-         */
-        if (test_tsk_need_resched(p))
-                rq->skip_clock_update = 1;
-}
+static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags);
 
 static inline int cpu_of(struct rq *rq)
 {
@@ -2118,6 +2108,31 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p,
                 p->sched_class->prio_changed(rq, p, oldprio, running);
 }
 
+static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
+{
+        const struct sched_class *class;
+
+        if (p->sched_class == rq->curr->sched_class) {
+                rq->curr->sched_class->check_preempt_curr(rq, p, flags);
+        } else {
+                for_each_class(class) {
+                        if (class == rq->curr->sched_class)
+                                break;
+                        if (class == p->sched_class) {
+                                resched_task(rq->curr);
+                                break;
+                        }
+                }
+        }
+
+        /*
+         * A queue event has occurred, and we're going to schedule.  In
+         * this case, we can save a useless back to back clock update.
+         */
+        if (test_tsk_need_resched(rq->curr))
+                rq->skip_clock_update = 1;
+}
+
 #ifdef CONFIG_SMP
 /*
  * Is this task likely cache-hot:
@@ -6960,6 +6975,8 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd)
         if (cpu != group_first_cpu(sd->groups))
                 return;
 
+        sd->groups->group_weight = cpumask_weight(sched_group_cpus(sd->groups));
+
         child = sd->child;
 
         sd->groups->cpu_power = 0;
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index f4f6a8326dd0..00ebd7686676 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1654,12 +1654,6 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
         struct cfs_rq *cfs_rq = task_cfs_rq(curr);
         int scale = cfs_rq->nr_running >= sched_nr_latency;
 
-        if (unlikely(rt_prio(p->prio)))
-                goto preempt;
-
-        if (unlikely(p->sched_class != &fair_sched_class))
-                return;
-
         if (unlikely(se == pse))
                 return;
 
@@ -1764,10 +1758,6 @@ static void pull_task(struct rq *src_rq, struct task_struct *p,
         set_task_cpu(p, this_cpu);
         activate_task(this_rq, p, 0);
         check_preempt_curr(this_rq, p, 0);
-
-        /* re-arm NEWIDLE balancing when moving tasks */
-        src_rq->avg_idle = this_rq->avg_idle = 2*sysctl_sched_migration_cost;
-        this_rq->idle_stamp = 0;
 }
 
 /*
@@ -2035,13 +2025,16 @@ struct sd_lb_stats {
         unsigned long this_load_per_task;
         unsigned long this_nr_running;
         unsigned long this_has_capacity;
+        unsigned int  this_idle_cpus;
 
         /* Statistics of the busiest group */
+        unsigned int  busiest_idle_cpus;
         unsigned long max_load;
         unsigned long busiest_load_per_task;
         unsigned long busiest_nr_running;
         unsigned long busiest_group_capacity;
         unsigned long busiest_has_capacity;
+        unsigned int  busiest_group_weight;
 
         int group_imb; /* Is there imbalance in this sd */
 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
@@ -2063,6 +2056,8 @@ struct sg_lb_stats {
         unsigned long sum_nr_running; /* Nr tasks running in the group */
         unsigned long sum_weighted_load; /* Weighted load of group's tasks */
         unsigned long group_capacity;
+        unsigned long idle_cpus;
+        unsigned long group_weight;
         int group_imb; /* Is there an imbalance in the group ? */
         int group_has_capacity; /* Is there extra capacity in the group? */
 };
@@ -2431,7 +2426,8 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
                 sgs->group_load += load;
                 sgs->sum_nr_running += rq->nr_running;
                 sgs->sum_weighted_load += weighted_cpuload(i);
-
+                if (idle_cpu(i))
+                        sgs->idle_cpus++;
         }
 
         /*
@@ -2469,6 +2465,7 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
         sgs->group_capacity = DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
         if (!sgs->group_capacity)
                 sgs->group_capacity = fix_small_capacity(sd, group);
+        sgs->group_weight = group->group_weight;
 
         if (sgs->group_capacity > sgs->sum_nr_running)
                 sgs->group_has_capacity = 1;
@@ -2576,13 +2573,16 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
                         sds->this_nr_running = sgs.sum_nr_running;
                         sds->this_load_per_task = sgs.sum_weighted_load;
                         sds->this_has_capacity = sgs.group_has_capacity;
+                        sds->this_idle_cpus = sgs.idle_cpus;
                 } else if (update_sd_pick_busiest(sd, sds, sg, &sgs, this_cpu)) {
                         sds->max_load = sgs.avg_load;
                         sds->busiest = sg;
                         sds->busiest_nr_running = sgs.sum_nr_running;
+                        sds->busiest_idle_cpus = sgs.idle_cpus;
                         sds->busiest_group_capacity = sgs.group_capacity;
                         sds->busiest_load_per_task = sgs.sum_weighted_load;
                         sds->busiest_has_capacity = sgs.group_has_capacity;
+                        sds->busiest_group_weight = sgs.group_weight;
                         sds->group_imb = sgs.group_imb;
                 }
 
@@ -2860,8 +2860,26 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
         if (sds.this_load >= sds.avg_load)
                 goto out_balanced;
 
-        if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
-                goto out_balanced;
+        /*
+         * In the CPU_NEWLY_IDLE, use imbalance_pct to be conservative.
+         * And to check for busy balance use !idle_cpu instead of
+         * CPU_NOT_IDLE. This is because HT siblings will use CPU_NOT_IDLE
+         * even when they are idle.
+         */
+        if (idle == CPU_NEWLY_IDLE || !idle_cpu(this_cpu)) {
+                if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
+                        goto out_balanced;
+        } else {
+                /*
+                 * This cpu is idle. If the busiest group load doesn't
+                 * have more tasks than the number of available cpu's and
+                 * there is no imbalance between this and busiest group
+                 * wrt to idle cpu's, it is balanced.
+                 */
+                if ((sds.this_idle_cpus  <= sds.busiest_idle_cpus + 1) &&
+                    sds.busiest_nr_running <= sds.busiest_group_weight)
+                        goto out_balanced;
+        }
 
 force_balance:
         /* Looks like there is an imbalance. Compute it */
@@ -3197,8 +3215,10 @@ static void idle_balance(int this_cpu, struct rq *this_rq)
                 interval = msecs_to_jiffies(sd->balance_interval);
                 if (time_after(next_balance, sd->last_balance + interval))
                         next_balance = sd->last_balance + interval;
-                if (pulled_task)
+                if (pulled_task) {
+                        this_rq->idle_stamp = 0;
                         break;
+                }
         }
 
         raw_spin_lock(&this_rq->lock);
diff --git a/kernel/sched_stoptask.c b/kernel/sched_stoptask.c
index 45bddc0c1048..2bf6b47058c1 100644
--- a/kernel/sched_stoptask.c
+++ b/kernel/sched_stoptask.c
@@ -19,14 +19,14 @@ select_task_rq_stop(struct rq *rq, struct task_struct *p,
 static void
 check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags)
 {
-        resched_task(rq->curr); /* we preempt everything */
+        /* we're never preempted */
 }
 
 static struct task_struct *pick_next_task_stop(struct rq *rq)
 {
         struct task_struct *stop = rq->stop;
 
-        if (stop && stop->state == TASK_RUNNING)
+        if (stop && stop->se.on_rq)
                 return stop;
 
         return NULL;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index b65bf634035e..5abfa1518554 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -702,7 +702,6 @@ static struct ctl_table kern_table[] = {
                 .extra1         = &zero,
                 .extra2         = &ten_thousand,
         },
-#endif
         {
                 .procname       = "dmesg_restrict",
                 .data           = &dmesg_restrict,
@@ -712,6 +711,7 @@ static struct ctl_table kern_table[] = {
                 .extra1         = &zero,
                 .extra2         = &one,
         },
+#endif
         {
                 .procname       = "ngroups_max",
                 .data           = &ngroups_max,
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index e04b8bcdef88..ea37e2ff4164 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -126,7 +126,7 @@ if FTRACE
 config FUNCTION_TRACER
         bool "Kernel Function Tracer"
         depends on HAVE_FUNCTION_TRACER
-        select FRAME_POINTER if (!ARM_UNWIND)
+        select FRAME_POINTER if !ARM_UNWIND && !S390
         select KALLSYMS
         select GENERIC_TRACER
         select CONTEXT_SWITCH_TRACER
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 82d9b8106cd0..c380612273bf 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -17,7 +17,6 @@
 #include <linux/writeback.h>
 #include <linux/kallsyms.h>
 #include <linux/seq_file.h>
-#include <linux/smp_lock.h>
 #include <linux/notifier.h>
 #include <linux/irqflags.h>
 #include <linux/debugfs.h>
@@ -1284,6 +1283,8 @@ void trace_dump_stack(void)
         __ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count());
 }
 
+static DEFINE_PER_CPU(int, user_stack_count);
+
 void
 ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
 {
@@ -1302,6 +1303,18 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
         if (unlikely(in_nmi()))
                 return;
 
+        /*
+         * prevent recursion, since the user stack tracing may
+         * trigger other kernel events.
+         */
+        preempt_disable();
+        if (__this_cpu_read(user_stack_count))
+                goto out;
+
+        __this_cpu_inc(user_stack_count);
+
+
+
         event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
                                           sizeof(*entry), flags, pc);
         if (!event)
@@ -1319,6 +1332,11 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
         save_stack_trace_user(&trace);
         if (!filter_check_discard(call, entry, buffer, event))
                 ring_buffer_unlock_commit(buffer, event);
+
+        __this_cpu_dec(user_stack_count);
+
+ out:
+        preempt_enable();
 }
 
 #ifdef UNUSED